The External Storage Support application enables you to mount external storage
services and devices as secondary Nextcloud storage devices. You may also allow
users to mount their own external storage services.

To create a new external storage mount, select an available backend from the
dropdown Add storage. Each backend has different required options, which
are configured in the configuration fields.

Each backend may also accept multiple authentication methods. These are selected
with the dropdown under Authentication. Different backends support different
authentication mechanisms; some specific to the backend, others are more
generic. See External Storage authentication mechanisms for more detailed
information.

When you select an authentication mechanism, the configuration fields change as
appropriate for the mechanism. The SFTP backend, for one example, supports
username and password, Log-in credentials, save in session, and RSA
public key.

Required fields are marked with a red border. When all required fields are
filled, the storage is automatically saved. A green dot next to the storage row
indicates the storage is ready for use. A red or yellow icon indicates
that Nextcloud could not connect to the external storage, so you need to
re-check your configuration and network availability.

If there is an error on the storage, it will be marked as unavailable for ten
minutes. To re-check it, click the colored icon or reload your Admin page.

A storage configured in a user’s Personal settings is available only to the user
that created it. A storage configured in the Admin settings is available to
all users by default, and it can be restricted to specific users and groups in
the Available for field.

Hover your cursor to the right of any storage configuration to expose
the settings button and trashcan. Click the trashcan to delete the
mountpoint. The settings button allows you to configure each storage mount
individually with the following options:

Encryption

Previews

Enable Sharing

Filesystem check frequency (Never, Once per direct access)

The Encryption checkbox is visible only when the Encryption app is enabled.

Enable Sharing allows the Nextcloud admin to enable or disable sharing on individual mountpoints.
When sharing is disabled the shares are retained internally, so that you can re-enable sharing
and the previous shares become available again. Sharing is disabled by default.

When using self-signed certificates for external storage mounts the certificate
must be imported into the personal settings of the user. Please refer to
Nextcloud HTTPS External Mount
for more information.

The following backends are provided by the external storages app. Other apps
may provide their own backends, which are not listed here. Google Drive and Dropbox
were moved to external apps which are still in development (Github-Repos for Google Drive and Dropbox).

Check Enable User External Storage to allow your users to mount their own
external storage services, and check the backends you want to allow. Beware, as
this allows a user to make potentially arbitrary connections to other services
on your network!

Nextcloud may not always be able to find out what has been
changed remotely (files changed without going through Nextcloud), especially
when it’s very deep in the folder hierarchy of the external storage.

You might need to setup a cron job that runs sudo-uwww-dataphpoccfiles:scan--all
(or replace “–all” with the user name, see also Using the occ command)
to trigger a rescan of the user’s files periodically (for example every 15 minutes), which includes
the mounted external storage.